Process for making cured foamed articles from epoxidized diene polymers

ABSTRACT

A process for curing and foaming epoxidized diene polymers which comprises contacting the polymer with a nonaromatic anhydride curing agent at an epoxy/anhydride molar ratio from 0.6 to 1.4 and from 2 to 10 phr of an accelerator at a temperature of from 100° to 200° C. for a period of 10 minutes to six hours.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional application Ser.No. 60/013,735, filed Mar. 20, 1996.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional application Ser.No. 60/013,735, filed Mar. 20, 1996.

FIELD OF THE INVENTION

This invention relates to the chemical curing of epoxidized dienepolymers. More particularly, the present invention relates to the use ofnonaromatic anhydride curing/foaming agents to make a cured foamedarticle.

BACKGROUND OF THE INVENTION

The chemical curing of epoxidized diene polymers is of interest forsealant, coatings, and adhesives applications. U.S. Pat. No.5,229,464describes low molecular weight epoxidized diene block copolymers andstates that they may be crosslinked by the addition of multifunctionalcarboxylic acids and acid anhydrides. U.S. Pat. Nos. 5,478,885 and5,461,112 describe similar polymers which are used as tougheningmodifiers for epoxy resins. These epoxidized diene polymers are shown tobe curable with carboxylic acid or anhydride curing agents. In thislatter application, partially and fully saturated aliphatic carboxylicacids or anhydrides have been found to be very useful and to allow theproduction of rigid, strong resins having enhanced toughness. Typically,one mole of anhydride or dicarboxylic acid is used for every mole ofepoxy functionality.

I have discovered that when such carboxylic acid anhydrides are used tocure these epoxidized diene polymers alone, especially in combinationwith amine or imidazole accelerating agents, bubbles form in thecrosslinked product. It has been found that the bubbles are produced asa result of the evolution of carbon dioxide during the decarboxylationof the anhydride. This side reaction competes with the crosslinkingreaction and the kinetics are such that it takes up enough of theanhydride groups to produce a significant volume of CO₂ bubbles in theproduct. The primary crosslinking reaction occurs simultaneously. Theresulting action of the anhydride or carboxylic acid is to both generatea foaming gas and to crosslink the polymer.

I have found that when the amount of amine or imidazole accelerator usedis increased approximately two to ten fold from its range of use in theaforementioned curing operation, the evolution of carbon dioxide andthus the bubbles dramatically increases. This causes sufficient foamingin the polymer product to produce a good quality cured foamed articlefrom the epoxidized diene polymer. These foamed products have goodadhesion to glass and range in physical character from soft, tacky foamsto rigid, nontacky foams.

SUMMARY OF THE INVENTION

This invention is a method for chemically curing and foaming epoxidizeddiene polymers. Further, the invention is a method of producing a foamwherein the curing agent acts both as a crosslinker and a blowing agent.The method involves curing said epoxidized diene polymers with partiallyor fully saturated nonaromatic carboxylic acid anhydrides. The anhydridecuring agent is used in a 0.6 to 1.4 molar ratio with the epoxyfunctionality. The curing process generally takes place at elevatedtemperatures, 100° to 200° C., for a period of 10 minutes to 6 hours andis often referred to as "bake cure." The preferred nonaromaticcarboxylic acid anhydride curing agents for use in the present inventionare methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, anddodecenylhydrophthalic anhydride. The anhydride bake cures areaccelerated by using an amine or imidazole curing accelerator which isused in an amount of 2 to 10 parts by weight (pbw) per 100 parts byweight of the polymer.

DETAILED DESCRIPTION OF THE INVENTION

Polymers containing ethylenic unsaturation can be prepared bycopolymerizing one or more olefins, particularly diolefins, bythemselves or with one or more alkenyl aromatic hydrocarbon monomers.The copolymers may, of course, be random, tapered, block or acombination of these, as well as linear, star or radial.

In general, when solution anionic techniques are used, copolymers ofconjugated diolefins, optionally with vinyl aromatic hydrocarbons, areprepared by contacting the monomer or monomers to be polymerizedsimultaneously or sequentially with an anionic polymerization initiatorsuch as group IA metals, preferably lithium, their alkyls, amides,silanolates, napthalides, biphenyls or anthracenyl derivatives. Thepolydienes are synthesized by anionic polymerization of conjugated dienehydrocarbons with these lithium initiators. This process is well knownas described in U.S. Pat. Nos. 4,039,593 and Re. 27,145 whichdescriptions are incorporated herein by reference. Polymerizationcommences with a monolithium initiator which builds a living polymerbackbone at each lithium site. Specific processes for making thepreferred polymers for use herein are described in detail in copending,commonly assigned application Ser. No. 08/320,807 filed Oct. 11, 1994,entitled "Monohydroxylated Diene Polymers and Epoxidized DerivativesThereof" and U.S. Pat. No. 5,461,112 which are herein incorporated byreference.

Conjugated diolefins which may be polymerized anionically include thoseconjugated diolefins containing from about 4 to about 24 carbon atomssuch as 1,3-butadiene, isoprene, piperylene, methylpentadiene,phenyl-butadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadieneand the like. Isoprene and butadiene are the preferred conjugated dienemonomers for use in the present invention because of their low cost andready availability. Alkenyl (vinyl) aromatic hydrocarbons which may becopolymerized include vinyl aryl compounds such as styrene, variousalkyl-substituted styrenes, alkoxy-substituted styrenes, vinylnapthalene, alkyl-substituted vinyl napthalenes and the like.

Epoxidized polymers which may be cured in accordance with the presentinvention are those described in U.S. Pat. Nos. 5,229,464, 5,247,026,5,478,885, and 5,461,112, which are all herein incorporated byreference. For instance, the following block copolymers containing from0.1 to 7.0 milliequivalents (meq) of epoxy per gram of polymer may beused:

    (A--B--A.sub.p).sub.n --Y.sub.r --(A.sub.q --B).sub.m

wherein Y is a coupling agent, coupling monomers or an initiator, andwherein A and B are polymer blocks which may be homopolymer blocks ofconjugated diolefin monomers, copolymer blocks of conjugated diolefinmonomers or copolymer blocks of conjugated diolefin monomers andmonoalkenyl aromatic hydrocarbon monomers, and wherein the A blocks havea greater number of di-, tri- and tetra-substituted unsaturation sitesper unit of block mass than do the B blocks, and wherein the A blockshave a weight average molecular weight from about 100 to about 3000 andthe B blocks have a weight average molecular weight from about 1000 toabout 15,000, and wherein p and q are 0 or 1 and n>0, r is 0 or 1, m≧0,and n+m ranges from 1 to 100.

The most highly preferred polymers for use herein are epoxidized diblockpolymers which fall within the scope of the formula:

    (HO).sub.x --A--S.sub.z --B--(OH).sub.y

wherein A and B are polymer blocks which may be homopolymer blocks ofconjugated diolefin monomers, copolymer blocks of conjugated diolefinmonomers, or copolymer blocks of diolefin monomers and monoalkenylaromatic hydrocarbon monomers. These polymers may contain up to 60% byweight of at least one vinyl aromatic hydrocarbon, preferably styrene.Generally, it is preferred that the A blocks should have a greaterconcentration of more highly substituted aliphatic double bonds than theB blocks have. Thus, the A blocks have a greater concentration of di-,tri-, or tetra-substituted unsaturation sites (aliphatic double bonds)per unit of block mass than do the B blocks. This produces a polymerwherein the most facile epoxidation occurs in the A blocks. The A blockshave a weight average molecular weight of from 100 to 6000, preferably500 to 4,000, and most preferably 1000 to 3000, and the B blocks have aweight average molecular weight of from 1000 to 15,000, preferably 2000to 10,000, and most preferably 3000 to 6000. S is a vinyl aromatichydrocarbon block which may have a molecular weight of from 100 to10,000. x and y are 0 or 1, but only one at a time can be1. z is 0 or1.

The overall weight average molecular weight of such diblocks may rangefrom 1500 to 15000, preferably 3000 to 7000. Either of the blocks in thediblock may contain some randomly polymerized vinyl aromatic hydrocarbonas described above. For example, where I represents isoprene, Brepresents butadiene, S represents styrene, and a slash (/) represents arandom copolymer block, the diblocks may have the following structures:

    I--B--OH I--B/S--OH I/S--B--OH I--I/B--OH or

    B/I--B/S--OH B--B/S--OH I--EB--OH I--EB/S--OH or

    I--S/EB--OH I/S--EB--OH HO--I--S/B HO--I--S/EB

where EB is hydrogenated butadiene, --EB/S--OH means that the hydroxylsource is attached to a styrene mer, and --S/EB--OH signifies that thehydroxyl source is attached to a hydrogenated butadiene mer. This lattercase, --S/EB--OH, requires capping of the S/EB "random copolymer" blockwith a mini EB block to compensate for the tapering tendency of thestyrene prior to capping with ethylene oxide. These diblocks areadvantageous in that they exhibit lower viscosity and are easier tomanufacture than the corresponding triblock polymers. It is preferredthat the hydroxyl be attached to the butadiene block because theepoxidation proceeds more favorably with isoprene and there will be aseparation between the functionalities on the polymer. Polymerscontaining no terminal hydroxyl functionality so that both x and y equal0 are also useful in the present invention.

Epoxidation of the base polymer can be effected by reaction with organicperacids which can be preformed or formed in situ. Suitable preformedperacids include peracetic and perbenzoic acids. In situ formation maybe accomplished by using hydrogen peroxide and a low molecular weightacid such as formic acid. These and other methods are described in moredetail in U.S. Pat. Nos. 5,229,464, 5,247,026, 5,478,885, and 5,461,112,which are herein incorporated by reference. The epoxidized polymers ofthis invention may contain from 0.1 to 7.0 meq of epoxy per gram ofpolymer depending upon the desired end use for the product.

The molecular weights of linear polymers or unassembled linear segmentsof polymers such as mono-, di-, triblock, etc., arms of star polymersbefore coupling are conveniently measured by Gel PermeationChromatography (GPC), where the GPC system has been appropriatelycalibrated. For anionically polymerized linear polymers, the polymer isessentially monodisperse (weight average molecular weight/number averagemolecular weight ratio approaches unity), and it is both convenient andadequately descriptive to report the "peak" molecular weight of thenarrow molecular weight distribution observed. Usually, the peak valueis between the number and the weight average, but for monodispersepolymers, all three are very similar. The peak molecular weight is themolecular weight of the main species shown on the chromatograph. Forpolydisperse polymers the weight average molecular weight should becalculated from the chromatograph and used. For materials to be used inthe columns of the GPC, styrene-divinyl benzene gels or silica gels arecommonly used and are excellent materials. Tetrahydrofuran is anexcellent solvent for polymers of the type described herein. Arefractive index detector may be used.

Measurement of the absolute molecular weight of a polymer is not asstraightforward or as easy to make using GPC. A good method to use forabsolute molecular weight determination is to measure the weight averagemolecular weight by light scattering techniques. The sample is dissolvedin a suitable solvent at a concentration less than 1.0 gram of sampleper 100 milliliters of solvent and filtered using a syringe and porousmembrane filters of less than 0.5 microns pore sized directly into thelight scattering cell. The light scattering measurements are performedas a function of scattering angle, polymer concentration and polymersize using standard procedures. The differential refractive index (DRI)of the sample is measured at the same wave length and in the samesolvent used for the light scattering. The following references areherein incorporated by reference:

1. Modern Size-Exclusion Liquid Chromatography, M. W. Yau, J. J.Kirkland, D. D. Bly, John Wiley and Sons, New York, N.Y., 1979.

2. Light Scattering From Polymer Solutions, M. B. Huglin, ed., AcademicPress, New York, N.Y., 1972.

3. W. K. Kai and A. J. Havlik, Applied Optics, 12, 541 (1973).

4. M. L. McConnell, American Laboratory, 63, May, 1978.

If desired, these block copolymers can be partially hydrogenated.Hydrogenation may be effected selectively as disclosed in U.S. Pat. No.Reissue 27,145 which is herein incorporated by reference. Thehydrogenation of these polymers and copolymers may be carried out by avariety of well established processes including hydrogenation in thepresence of such catalysts as Raney Nickel, nobel metals such asplatinum and the like, soluble transition metal catalysts and titaniumcatalysts as in U.S. Pat. No. 5,039,755 which is also incorporated byreference. The polymers will have different diene blocks and these dieneblocks may be selectively hydrogenated as described in U.S. Pat. No.5,229,464 which is also herein incorporated by reference.

U.S. Pat. Nos. 5,478,885 and 5,461,112 describe anhydride curing agentsas commonly used to cure the epoxidized diene polymers described above.Anhydrides are used herein because a bake cure system is desired. Aminecuring agents, which work well in compositions containing epoxy resinsas described in said patent, will not cure epoxidized diene polymers.The anhydride curing agents described as useful in said patents may beany compound containing one or more anhydride functional groups andspecific examples given include phthalic anhydride, substituted phthalicanhydrides, hydrophthalic anhydrides (which are not aromatic compoundsbecause they are hydrogenated), substituted hydrophthalic anhydrides,succinic anhydride, substituted succinic anhydrides, halogenatedanhydrides, multifunctional carboxylic acids, and polycarboxylic acids.

Because of their ease of handling, saturated or partially saturatedanhydrides, such as hydrophthalic anhydrides and substitutedhydrophthalic anhydrides, are regularly used in this type of curing. Ihave found that, unknown to those skilled in the art, these and othernonaromatic anhydrides have secondary effects when used to cureepoxidized diene polymers in high concentration. Sufficient carbondioxide is generated during the reaction of the accelerator and thecuring agent to form enough bubbles in the cured product to provide afoam. Non aromatic carboxylic acid anhydride curing agents are useful inthe present invention. Preferred curing agents are the substituted andunsubstituted hydrophthalic anhydrides. The most preferred curing agentsare methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, anddodecenylhydrophthalic anhydride.

I have found that it is necessary to use an anhydride curing agent whichis nonaromatic in nature to achieve a good bake cure with the formationof sufficient bubbles in the product. Carbon dioxide is not generated inthe reaction of an epoxidized diene polymer and an aromatic anhydridecuring agent. According to my invention, the nonaromatic anhydride iscombined with the epoxidized diene polymer such that a suitableepoxy/anhydride molar ratio is achieved. This ratio should range from0.6 to 1.4, preferably 0.8 to 1.2, and most preferably about 1.0, toachieve sufficient crosslinking and foaming to produce a product withdesirable foam characteristics. The crosslinking occurs through theepoxy groups and aromatic anhydride such that nonaromatic ester linkagesare formed. Typically, the anhydride cures are conducted at elevatedtemperatures--temperatures of from 100°to 200° C. are possible but 130°to 180° C. is the preferred operating range--for a period of 10 minutesto 6 hours, and are often referred to as "bake cures."

The anhydride bake cures are accelerated by using a curing accelerator.Suitable curing accelerators include trialkyl amines,hydroxyl-containing compounds and imidazoles. Benzyldimethylamine(BDMA), and 2-ethyl-4-methylimidazole (EMI) have been found to work wellin curing the blends of the present invention. The accelerator is usedin an amount of 1 to 10, preferably about 10 parts of accelerator per100 parts of polymer.

The crosslinked materials of the present invention are useful inadhesives (including pressure sensitive adhesives, contact adhesives,laminating adhesives, assembly adhesives and structural adhesives),sealants, films (such as those requiring heat and solvent resistance),etc. However, it may be necessary for a formulator to combine a varietyof ingredients together with the polymers of the present invention inorder to obtain products having the proper combination of properties(such as adhesion, cohesion, durability, low cost, etc.) for particularapplications. Thus, a suitable formulation might contain only thepolymers of the present invention and the nonaromatic anhydride curingagent. This is especially true for sealants and structural adhesives.However, in applications such as pressure sensitive adhesives, suitableformulations would also contain various combinations of resins,plasticizers, fillers, solvents, stabilizers and other ingredients suchas asphalt. The following are some typical examples of formulatingingredients for adhesives and sealants.

In adhesive applications, as well as in sealants, it may be necessary toadd an adhesion promoting or tackifying resin that is compatible withthe polymer. A common tackifying resin is a diene-olefin copolymer ofpiperylene and 2-methyl-2-butene having a softening point of about 95°C. This resin is available commercially under the tradename Wingtack® 95and is prepared by the cationic polymerization of 60% piperlene, 10%isoprene, 5% cyclo-pentadiene, 15% 2-methyl-2-butene and about 10%dimer, as taught in U.S. Pat. No. 3,577,398. Other tackifying resins maybe employed wherein the resinous copolymer comprises 20-80 weightpercent of piperylene and 80-20 weight percent of 2-methyl-2-butene. Theresins normally have ring and ball softening points as determined byASTM method E28 between about 80° C. and 115° C.

Saturated resins may also be employed as reinforcing agents, providedthat they are compatible with the particular polymer used in theformulation. Normally, these resins should also have ring and ballsoftening points between about 80° C. and 115° C. although mixtures ofaromatic resins having high and low softening points may also be used.Useful resins include coumarone-indene resins, polystyrene resins, vinyltoluene-alpha methylstyrene copolymers and polyindene resins. Examplesof such reinforcing resins useful in the present invention are thehydrogenated Regalrez® and Regalite® resins from Hercules. Preferably,they are used in amounts from 1 to 50 percent by weight of the totalcomposition.

Other resins which are also useful in the compositions of this inventioninclude hydrogenated rosins, esters of rosins, polyterpenes,terpenephenol resins and polymerized mixed olefins, lower softeningpoint resins and liquid resins. An example of a liquid resin is Adtac®LV resin from Hercules. To obtain good thermo-oxidative and colorstability, it is preferred that the tackifying resin be a saturatedresin, e.g., a hydrogenated dicyclopentadiene resin such as Escorez®5000 series resin made by Exxon or a hydrogenated polystyrene orpolyalphamethylstyrene resin such as Regalrez® resin made by Hercules.The amount of adhesion promoting resin employed varies from 0 to 400parts by weight per hundred parts rubber (phr), preferably between 20 to350 phr, most preferably 20 to 150 phr. The selection of the particulartackifying agent is, in large part, dependent upon the specific polymeremployed in the respective adhesive composition.

Reactive co-curing components such as epoxy resins and epoxidizednatural products are also useful as reinforcing agents. Examples ofuseful epoxy resins are aromatic resins such as EPON® 828 resin fromShell and aliphatic resins such as EPONEX® 1510 resin from Shell and UVR6110 resin from Union Carbide. Examples of useful epoxidized orepoxy-containing natural products are the DRAPEX® series of epoxidizedoils from Witco and naturally occurring vernonia oil.

A composition of the instant invention may contain plasticizers, such asrubber extending plasticizers, or compounding oils or organic orinorganic pigments and dyes. Rubber compounding oils are well-known inthe art and include both high saturates content oils and high aromaticscontent oils. Preferred plasticizers are highly saturated oils, e.g.Tufflo® 6056 and 6204 oil made by Arco and process oils, e.g. Shellflex®371 oil made by Shell. Reactive compounds can be used as plasticizers.The amounts of rubber compounding oil employed in the inventioncomposition can vary from 0 to about 500 phr, preferably between about 0to about 100 phr, and most preferably between about 0 and about 60 phr.

Optional components of the present invention are stabilizers whichinhibit or retard heat degradation, oxidation, skin formation and colorformation. Stabilizers are typically added to the commercially availablecompounds in order to protect the polymers against heat degradation andoxidation during the preparation, use and high temperature storage ofthe composition. Additional stabilizers known in the art may also beincorporated into the composition. These may be for protection duringthe life of the article against, for example, oxygen, ozone andultra-violet radiation. However, these additional stabilizers should becompatible with the essential stabilizers mentioned hereinabove andtheir intended function as taught herein.

Various types of fillers and pigments can be included in theformulation. This is especially true for exterior sealants in whichfillers are added not only to create the desired appeal but also toimprove the performance of the sealants such as its weatherability. Awide variety of fillers can be used. Suitable fillers include calciumcarbonate, clays, talcs, silica, zinc oxide, titanium dioxide and thelike. The amount of filler usually is in the range of 0 to about 65%wbased on the solvent free portion of the formulation depending on thetype of filler used and the application for which the sealant isintended. An especially preferred filler is titanium dioxide.

All adhesive and sealant compositions based on the epoxidized polymersof this invention will contain some combination of the variousformulating ingredients disclosed herein. No definite rules can beoffered about which ingredients will be used.

The skilled formulator will choose particular types of ingredients andadjust their concentrations to give exactly the combination ofproperties needed in the composition for any specific adhesive orsealant application.

The only three ingredients that will always be used in any adhesive,coating or sealant are the epoxidized polymer, the curing agent, and theaccelerator. Beyond these three ingredients, the formulator will chooseto use or not to use among the various resins, fillers and pigments,plasticizers, reactive oligomers, reactive and nonreactive diluents,stabilizers, and solvents.

Adhesives are frequently thin layers of sticky compositions which areused in protected environments (adhering two substrates together).Therefore, unhydrogenated epoxidized polymers will usually have adequatestability so resin type and concentration will be selected for maximumstickiness without great concern for stability, and pigments willusually not be used.

Sealants are gap fillers. Therefore, they are used in fairly thicklayers to fill the space between two substrates. Since the twosubstrates frequently move relative to each other, sealants are usuallylow modulus compositions capable of withstanding this movement. Further,they generally have good adhesion to the substrates. Since sealants arefrequently exposed to the weather, the hydrogenated epoxidized polymersare usually used. Resins and plasticizers will be selected to maintainlow modulus and minimize dirt pick-up. Fillers and pigment will beselected to give appropriate durability and color. Since sealants areapplied in fairly thick layers, solvent content is as low as possible tominimize shrinkage. The present invention is seen to produce aparticularly good sealant, the foaming character of such sealants willenhance their gap filling ability.

A formulator skilled in the art will see tremendous versatility in theepoxidized polymers of this invention to prepare adhesives, coatings andsealants having properties suitable for many different applications.

The adhesive and sealant compositions of the present invention can beprepared by mixing the components together until a homogeneous blend isobtained. Various methods of blending are known to the art and anymethod that produces a homogenous blend is satisfactory. Frequently, thecomponents can be blended together using solvent to control viscosity.Suitable solvents include common hydrocarbons, esters, ethers, ketonesand alcohols as well as mixtures thereof. If solvent content isrestricted or in solvent-free compositions, it may be possible to heatthe components to help reduce viscosity during mixing and application.

A preferred use of the present formulation is in weatherable bake-curedsealants. The sealant comprises a monohydroxylated epoxidized dienepolymer, an acid anhydride curing agent, an optional curing accelerator,an optional reinforcing resin or co-curing agent, and an optionaltackifying resin. Alternatively, when the amount of tackifying resin iszero, the compositions of the present invention may be used foradhesives that do not tear paper and molded goods and the like.

Sealant compositions of this invention can be used for manyapplications. Particularly preferred is their use as gap fillers forconstructions which will be baked (for example, in a paint baking oven)after the sealant is applied. This would include their use in automobilemanufacture and in appliance manufacture. Another preferred applicationis their use in gasketing materials, for example, in lids for food andbeverage containers.

EXAMPLE

One formulation each were made with polymers 206 and 112. Polymer 206 isa linear saturated I--S/EB--OH block copolymer having 42 percentstyrene, an epoxy equivalent weight of 670 g/eq epoxy, a hydroxylequivalent weight of 6000 g/eq hydroxyl, and a number average molecularweight of 6000. Polymer 112 was a linear unsaturated I--B blockcopolymer having an epoxy equivalent weight of 208 g/eq epoxy, abutadiene to isoprene ratio of 19, and a number average molecular weightof 5,400.

Formulations 1 and 2 below were used in this example. MTHPA is methyltetrahydrophthalic anhydride, the curing agent, and EMI is2-ethyl-4-methyl imidazole, the accelerator.

    ______________________________________                                        Formulation 1    Formulation 2                                                ______________________________________                                        Polymer 206                                                                           100      grams    Polymer 12                                                                            100   grams                                 MTHPA   24.2     grams    MTHPA   81.3  grams                                 EMI     9.1      grams    EMI     30.6  grams                                 ______________________________________                                    

These formulations were mixed at 100° to 120° C. and then placed in 6"diameter fiber tube and cured at 150° C. for two hours. The polymer 206formulation resulted in a brown foam. The foam was soft and flexible andhad a slightly tacky surface. The polymer 112 formulation produced arigid, nontacky foam. Both cured foams exhibited good adhesion to thefiber container.

Portions of both formulations were also cured at 150° C. for two hoursin glass containers. The cured foams exhibited good adhesion to glass.

I claim:
 1. A process of making a cured foamed article from anepoxidized diene polymer which comprises contacting the polymer with apartially or fully saturated nonaromatic anhydride curing agent at anepoxy/anhydride molar ratio of from 0.6 to 1.4 and from 2 to 10 pbw ofan accelerator at a temperature of from 100° to 200° C. for a period of10 minutes to 6 hours.
 2. The process of claim 1 wherein the curingagent is selected from the group consisting of substituted andnonsubstituted hydrophthalic anhydrides.
 3. The process of claim 2wherein the curing agent is selected from the group consisting ofmethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, anddodecenylphthalic anhydride.
 4. The process of claim 1 where thestructure of the epoxidized polydiene is (HO)_(x) --A--S_(z)--B--(OH)_(y) wherein A and B are polymer blocks which may behomopolymer blocks of conjugated diolefin monomers, copolymer blocks ofconjugated diolefin monomers, or copolymer blocks of diolefin monomersand monoalkenyl aromatic hydrocarbon monomers.
 5. The process of claim 4where x=0, y=1, z=0, and block B is comprised of styrene and butadieneand block A is comprised of isoprene.
 6. The process of claim 4 wherex=0, y=0, z=0, and block B is comprised of butadiene and block A iscomprised of isoprene.
 7. The process of claim 1 wherein the epoxidizeddiene polymer contains from 0.1 to 7.0 meq/g of epoxy per gram ofpolymer.
 8. The process of claim 1 wherein the accelerator is selectedfrom the group consisting of 2-ethyl-4-methyl-imidazole andbenzyl-dimethyl-amine.
 9. The process of claim 1 wherein the temperatureranges from 130° C. to 160° C.
 10. A foamed article from an epoxidizeddiene polymer produced by the process of claim
 1. 11. A crosslinkedepoxidized polydiene polymer wherein the crosslinking in the polymer isthrough nonaromatic ester linkages and the polymer contains from 0.1 to7.0 meq per gram of original epoxidized polymer of said ester linkages.12. A pressure sensitive adhesive composition comprising the crosslinkedpolymer of claim 10 and a tackifying resin.
 13. A sealant compositioncomprising the crosslinked polymer of claim
 11. 14. A structuraladhesive composition comprising the crosslinked polymer of claim 11.